The field of this invention relates to measuring sticks and more particularly to a foldable measuring stick which is formed of an extended length, six feet and longer, and usable in the construction industry to check grades in the constructing of dams, roads and hillsides.
In the construction industry, in the moving of dirt, telescope leveling instruments are in common use such as a transit. The leveling instrument is used in combination with an elongated measuring stick. The leveling instrument is mounted in a horizontal plane and then a person, usually referred to as a grade checker, is located at a location spaced from the instrument and holds an elongated measuring stick. This measuring stick has printed thereon a measure table such as inches and feet, or a metric table. The bottom of the stick is placed against the dirt grade and a person looking through the transit can visually observe the measure table thereby noting the particular measuring point on the table which coincides with the horizontal position of the transit. By using this information, the grade level can be determined.
The grade level measuring sticks are usually 6 feet long and frequently 8 feet long and at times it would be desirable to have such sticks to be of a longer length as at times a 30 foot measuring stick would be preferable.
Such extended length of measuring sticks does not facilitate portability. Such sticks are difficult to carry around on a person and are difficult to carry in an automobile. It is not uncommon for a grade checker to put such a stick on the ground, when not in use, and have the stick run over by a piece of construction equipment.
In order to overcome the disadvantage of a solid measuring stick, it has been common for grade checkers to use the common type of folding ruler. However, this ruler is usually formed of a thin sheet material, such as wood, and the ruler tends to bend during use which can give inaccurate readings. Also, such a ruler breaks easily and it takes a substantial amount of time in order to unfold the ruler and to collapse the ruler.
Grade checkers usually work around heavy construction equipment and this type of equipment frequently has a cab which is mounted several feet off the ground. A person walking around amongst this equipment, such as a grade checker, may not be readily seen by operators of this heavy equipment. However, if a flag, or some other type of visual identification means could be mounted on the top of the measuring stick, and the measuring stick was of an extended length, that such a device would act as a safety precaution against the grade checker being injured by the heavy equipment and that the grade checker would be more easily observed to the operators of the equipment. To place such a flag on on the foldable rule, which is now frequently employed, would not be convenient. Also, such foldable rules rarely exceed six feet in length and an eight foot length would be the minimum length needed to be observable by the operators of the heavy equipment.
Previously, there has been an attempt to design a collapsible measuring stick which employs a plurality of telescoping rods. However, this structure is quite complex and therefore costly to manufacture. Also, the time involved in moving the telescoping rods to the extended length is more than a few seconds. If one of the telescoping rods is not fully telescoped, the measuring stick can give inaccurate readings.